This interrupted case study is an exploration of ornithine transcarbamylase (OTC) deficiency, which results from a genetic defect in a urea cycle enzyme. Students are introduced to a 21-year-old patient who loses consciousness after a gym session. Upon investigation of the man’s signs and symptoms, students apply their knowledge of nitrogen metabolism, the urea cycle, and how the latter is linked to the Krebs cycle to diagnose and treat the patient. Before beginning the case, students are expected to have some basic knowledge of amino acids, general metabolism, and genetics, as it is designed for an upper-level undergraduate course in biochemistry. The case incorporates multiple levels of analysis, from simple recall to synthesizing and applying information. The case can be used for either in-person or online course offerings, and can be implemented via group work or individually. Part of the case can also be assigned prior to class, or it can be fully completed within class time, ending with an optional discussion of OTC deficiency.